First Results from the NPDGamma Experiment at the Spallation Neutron Source

The NPDGamma experiment aims to measure the parity-odd correlation between
the neutron spin and the direction of the emitted photon in neutron-proton
capture. A parity violating asymmetry from this process can be directly
related to the strength of the hadronic weak interaction between nucleons.

The methodology and results from the first run of this experiment, completed
at LANSCE in 2006, will be summarized. The next phase of the experiment has
finished a very successful commissioning on the Fundamental Neutron Physics
Beamline of the Spallation Neutron Source at ORNL. We will discuss the
improvements in the apparatus and show results from the commissioning data.
The upcoming run is expected to yield a measurement with a projected
statistical error of 1x10$^{-8}$ as well as negligible systematic errors.
This result will finally test the theoretical predictions.